In the art of controlling internal combustion engines, it may be desired to use an existing electronic control module (ECM) to control operation of a new or existing engine to reduce production costs and product development time. Problems arise, however, if the electronic control module cannot accommodate system requirements. One such situation arises in the development of dual fuel engines that operate in either a dual fuel mode or a diesel fuel mode. For the dual fuel mode, a gaseous fuel such as natural gas is controllably released into an air intake port connected to a cylinder, producing an air/fuel mixture. After a predetermined period of time, a small amount of diesel fuel is injected into the cylinder containing the air/fuel mixture. The compression ignites the diesel fuel, which in turn ignites the air/fuel mixture. The dual fuel engine has a solenoid gaseous fuel admission valve (SOGAV) for metering the natural gas along with an electronic unit injector (EUI) for injecting diesel fuel for each cylinder. Thus, control systems for dual fuel engines must control twice the number of device drivers per cylinder, one for the SOGAV and one for the EUI. Further, the SOGAVs require a relatively long duration of time to admit the required amount of gaseous fuel, and multiple SOGAVs may therefore be open simultaneously. Electronic engine control modules designed for engines that operate with one type of fuel typically control only one injector per cylinder and therefore may not be equipped to accommodate all of the SOGAVs and EUIs of the dual fuel engine.
Another situation where one electronic control module may not meet requirements of an application arises where it is desired to use a particular engine model, but the engine does not deliver the required amount of power. The engine may be a dual fuel engine, or conventional engine that operates continuously on one type of fuel. The most economical solution may be to use two engines, instead of switching to a larger engine or re-engineering the existing engine to deliver more power. In these situations, it is necessary to synchronize control of the engines so that they operate together efficiently. A problem arises if the existing electronic control module is not designed to accommodate the number fuel injectors present between the two engines. For example, two engines may include a total of 16 cylinders, each cylinder having an EUI, but the existing electronic control module may be designed to accommodate only 12 cylinders. Thus, the existing electronic control module does not have means to inject fuel in 4 cylinders.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.